Disposable pull-on undergarment

ABSTRACT

A disposable pull-on undergarment 1 having front and rear waist regions bonded together along longitudinally bonding zones to define a waist-hole and a pair of leg-holes. The respective bonding zones have an upper end lying most adjacent the waist-hole and a lower end lying most adjacent the leg-holes and extend from the upper ends toward the lower ends so that these bonding zones get nearer to a longitudinal center line X.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a disposable pull-on undergarment andmore particularly to a pull-on undergarment such as a disposablepants-type diaper, training pants or incontinent pants.

[0002] Conventional disposable pull-on undergarments are composed offront and rear waist regions opposed to each other and a crotch regionextending between these two waist regions. The front and rear waistregions are connected with each other in bonding zones extending alongtransversely opposite side edge portions thereof so as to define awaist-hole and a pair of leg-holes. Such undergarment is disclosed, forexample, in Japanese Patent Application Publication Nos. 1998-75980A,1998-99373A and 1998-204704A. Commonly to these undergarments, therespective bonding lines extend along transversely opposite sides of awearer's waist.

[0003] To take off the used undergarment from the wearer lying on his orher back, a helper for this wearer may tear open the undergarment alongthe bonding zones. A force required for the helper to tear open the usedundergarment is exerted on the undergarment in a direction from sideedges of the waist-hole a transversely middle zone of the undergarmentin the crotch region.

[0004] In the case of the article disclosed in these Publications, thedirection of the tearing force is out of coincidence with the directionof the bonding lines. In other words, the force is exerted upon thezones other than the bonding lines as the used undergarment is torn openand consequently there is an anxiety that the undergarment could not besmoothly torn open along the bonding lines.

SUMMARY OF THE INVENTION

[0005] It is an object of this invention to provide a disposable pull-onundergarment improved so that the undergarment can be smoothly torn openalong the bonding lines.

[0006] According to this invention, there is provided a disposablepull-on undergarment having front and rear waist regions opposed to eachother and a crotch region extending between these two waist regionswherein these front and rear waist regions are connected with each otherin bonding zones extending along transversely opposite side edgeportions thereof so as to define a waist-hole and a pair of leg-holes.

[0007] The improvement of this invention is in that the bonding linesrespectively have upper end portions lying adjacent the waist-hole andlower end portions lying adjacent the pair of leg-holes so that thebonding lines get nearer to a longitudinal center line verticallyextending across a circumferential middle zones of the front and rearwaist regions as the bonding lines extend from the upper end portionstoward the lower end portion.

[0008] According to one preferred embodiment of this invention, thebonding lines extend at an angle of 5˜30° with respect to thelongitudinal center line.

[0009] According to another preferred embodiment of this invention, theundergarment comprises a liquid-pervious topsheet, a liquid-imperviousbacksheet and a liquid-absorbent panel disposed between these twosheets.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a perspective view showing a disposable diaper as atypical embodiment of this invention as viewed from the side a frontwaist region and partially broken away;

[0011]FIG. 2 is an exploded plan view showing the diaper of FIG. 1 asbefore pants-shaped;

[0012]FIG. 3 is a sectional view taken along a line A-A in FIG. 2;

[0013]FIG. 4 is a diagram illustrating a manner in which the diaper istaken off from the wearer's body;

[0014]FIG. 5 is a view similar to FIG. 1 but showing another embodimentof the diaper; and

[0015]FIG. 6 is an exploded plan view showing the diaper of FIG. 5 asbefore pants-shaped.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Details of a disposable pull-on undergarment according to thisinvention will be more fully understood from the description of adisposable pants-type diaper as a typical embodiment given hereunderwith reference to the accompanying drawings.

[0017]FIG. 1 is a perspective view showing a disposable pull-on diaper 1as viewed from the side of a front waist region 20 and partially brokenaway, FIG. 2 is an exploded plan view of the diaper 1 shown by FIG. 1 asbefore the diaper 1 is shaped into pants and FIG. 3 is a sectional viewtaken along a line A-A in FIG. 2.

[0018] The diaper 1 basically comprises a liquid-pervious topsheet 2, aliquid-impervious backsheet 3 and a liquid-absorbent panel 4 disposedbetween the top- and backsheets 2, 3. The liquid-absorbent panel 4 hasits entire surface covered with and bonded to liquid-pervious tissuepaper (not shown) and this panel 4 is bonded to inner surface of atleast one of the top- and backsheets 2, 3 via the tissue paper.

[0019] As seen in FIG. 2, the diaper 1 is longitudinally composed of afront waist region 20, a rear waist region 22 and a crotch region 21extending between said front and rear waist regions 20, 22. The diaper 1is contoured by transversely opposite side edge portions 1 a, 1 b, 1 cextending in longitudinal direction of the diaper 1 and longitudinallyopposite end portions 1 d, 1 e extending in transverse direction of thediaper 1. The side edge portions 1 c in the crotch region 21 curvetransversely inward so as to describe circular arcs. The side edgeportions 1 a, 1 b, 1 c are respective provided with leak-barrier cuffs 8each extending in the longitudinal direction of the diaper 1.

[0020] In the diaper 1, the end portions 1 d, 1 e of the front and rearwaist regions 20, 22, respectively, are dimensioned to be substantiallyequal to each other. The transversely opposite side edge portions 1 a ofthe front waist region 20 extend from the end portion id toward thecrotch region 21 so that these side edge portions 1 a get nearer to alongitudinal center line x bisecting a dimension defined between thetransversely opposite edge portions 1 a, 1 b, 1 c. On the contrary, thetransversely opposite side edge portions 1 b of the rear waist region 22extend from the end portion 1 e toward the crotch region 21 so thatthese side edge portions 1 b get away from the longitudinal center lineX.

[0021] To shape the diaper 1 from its state shown by FIG. 2 into thedesired pull-on undergarment, the diaper 1 is folded with its innersurface inside along a transverse center line Y bisecting a dimensiondefined between the longitudinally opposite end portions 1 c, 1 d of thediaper 1. Then the transversely opposite side edge portions 1 a, 1 b ofthe front and rear waist regions 20, 22, respectively, are put flat andbonded together. In the diaper 1 having been pants-shaped, a waist-hole6 opens upward as viewed in FIG. 1, a pair of leg-holes 7 open right-and leftward, respectively, also as viewed in FIG. 1, respectively, anda pair of bonding zones 5 extend along the transversely opposite sideedge portions 1 a, 1 b of the front and rear waist regions 20, 22.

[0022] Each of the bonding zones 5 comprises an upper end section 5 aextending adjacent the waist-hole 6 and a lower end section 5 bextending adjacent the associated leg-hole 7. The bonding zone 5 extendfrom the upper section 5 a toward the lower end section 5 b so that thebonding zone 5 get nearer to and obliquely of the longitudinal centerline X.

[0023] Two-dotted chain lines Z in FIG. 1 indicate imaginary positionsof the bonding zones 5 on the assumption that the bonding zones 5 havebeen translated toward the longitudinal center line X and intersectedthe longitudinal center line X preferably at an angle θ of 5˜30°,respectively.

[0024] With the diaper 1 put on a wearer's body, the upper end portions5 a of the respective bonding zones 5 lie at transversely lateral sidesof the wearer and the lower end portions 5 b of the respective bondingzones 5 lie on the belly of the wearer. Each of the bonding zones 5comprises a plurality of heat-sealed lines 5 c intermittently arrangedin the longitudinal direction of the diaper 1.

[0025] Each of the cuffs 8 basically comprises a fixed side edge portion8 a fixed to the topsheet 2, a free side edge portion 8 b opposed to thefixed side edge portion 8 a and extending in the longitudinal directionand longitudinal opposite end portions 8 c collapsed inward transverselyof the diaper 1 and bonded to the topsheet 2 in such collapsed state. Inthe rear waist region 22, the fixed side edge portion 8 a furtherextends transversely outward to define an outer extension 8 d. Alongitudinally extending elastically stretchable member 9 is bondedunder tension to the free side edge portion 8 b of the cuff 8 in amanner that the elastically stretchable member 9 is wrapped by a part ofthe free side edge portion 8 b. The cuff 8 is normally biased by theelastically stretchable member 9 to rise from the topsheet 2.

[0026] Elastic member 10 comprising a plurality of elastic elementswhich are circumferentially stretchable is bonded under tension toperipheral edge of the waist-hole 6. Portions of the elastic member 10lying on the transversely opposite side edge portions 1 a of the diaper1 are disposed between the transversely opposite side edge portions 3 aof the backsheet 3 and the outer extensions 8 d of the respective cuffs8 and bonded to at least one of these portions 3 a, 8 d. Remainingportions are disposed between the top- and backsheets 2, 3 and bonded toat least one of these sheets 2, 3.

[0027] An elastic member 11 comprising a plurality of elastic elementswhich are circumferentially stretchable is bonded under tension to eachof the leg-holes 7 along peripheral edge thereof. The elastic member 11associated with the leg-hole 7 actually consists of a first elasticmember 11 a and a second elastic member 11 b. These first and secondelastic members 11 a, 11 b respectively have sections 11 a ₁, 11 b ₁extending transversely across substantially middle zone of the crotchregion 21, on one hand, and sections 11 a ₂ 11 b ₂ extending along thetransversely opposite side edge portions 1 c of the diaper 1 in thecrotch region 21. The respective sections 11 a ₁, 11 b ₁ of these firstand second elastic members 11 a, 11 b are disposed between the backsheet3 and the panel 4 and bonded to the backsheet 3 while the respectivesections 11 a ₂, 11 b ₂ of these first and second elastic members 11 a,11 b are disposed between and bonded to the transversely opposite sideedge portions 3 a of the backsheet 3 and the outer extension 8 d of thecuff 8.

[0028] Referring to FIG. 1, a plurality of gathers are formed along theperipheral edge of the waist-hole 6, the peripheral edges of theleg-holes 7 and the free side edge portions 8 b of the cuffs 8 and thefree side edge portions 8 b rise from the topsheet 2 as the respectiveelastic members 9, 10, 11 contract.

[0029] Along the transversely opposite side edge portions 1 a, 1 b, 1 cof the diaper 1, the transversely opposite side edge portions 2 a of thetopsheet 2 transversely extend outward slightly beyond the transverselyopposite side edges of the panel 4 and the transversely opposite sideedge portions 3 a of the backsheet 3 as well as the outer extensions 8 dof the cuffs 8 further extend transversely outward beyond thetransversely opposite side edge portions 2 a of the topsheet 2. Thetransversely opposite side edge portions 2 a are disposed between thetransversely opposite side edge portions 3 a and the outer extensions 8d and bonded to at least one of them. The side edge portions 3 a and theouter extensions 8 d are put flat and bonded together. Along thelongitudinally opposite end portions 1 d, 1 e, portions of the top- andbacksheets 2, 3 extending transversely outward beyond longitudinallyopposite ends of the panel 4 are put flat and bonded together.

[0030]FIG. 4 illustrates a manner in which the diaper 1 is taken offfrom the wearer's body lying on the back. As illustrated, the helper maygrasp the end portion 1 d of the diaper 1 with his or her left hand andthe end portion 1 e of the diaper 1 with his or her right hand. To takethe diaper 1 from the wearer s body, the side edge portions 1 a or theside edge portions 1 b may be torn open from the waist-hole 6 toward theleg-holes 7 by pulling the left hand grasping the end portion 1 d in thefront waist region 20 toward the helper's own left flank with the endportion 1 e in the rear waist region 22 held by the right hand. Then,with the end portion 1 e held by the left hand, the other side edgeportions 1 b or 1 a may be torn open from the waist-hole 6 toward theleg-holes 7 by pulling the right hand grasping the end portion 1 d inthe front waist region 20 toward the helper's own right flank.

[0031] A direction in which a force is exerted on the diaper 1 to tearopen this is substantially coincident with the direction in which therespective bonding zones 5. Consequently, the diaper 1 can be smoothlytorn open along the respective bonding zones 5 without an anxiety thatthe force might be exerted on any other zones than the bonding zones 5.According to this diaper 1, the angle θ at which the respective bondingzones 5 intersect the longitudinal center line X may be varied within arange of 5˜30° to adjust a slant of the zones 5 with respect to thelongitudinal center line X.

[0032]FIG. 5 is a perspective view showing an alternative embodiment ofthe disposable diaper 1 according to this invention as viewed from theside of the front waist region 20 and FIG. 6 is an exploded plan viewshowing the diaper 1 of FIG. 5 as before the diaper 1 is pants-shaped.The diaper 1 of FIG. 5 basically comprises the similar members to thoseconstituting the diaper 1 of FIG. 1 and no description in detail isgiven hereunder.

[0033] According to this embodiments the transversely opposite side edgeportions 1 a in the front waist region 20 as well as the transverselyopposite side edge portions 1 b in the rear waist regions 22 extend inparallel to each other and an auxiliary elastic member 12 comprising aplurality of elastic elements is bonded under tension to the diaper 1 soas to extend transversely across the front waist region 20 between theelastic member 10 associated with the waist-hole and the elastic members11 associated with the respective leg-holes. The auxiliary elasticmember 12 has its stretch stress gradually increasing from its element12 a lying most adjacent the elastic member 10 associated with thewaist-hole toward its element 12 d lying most adjacent the elasticmembers 11 associated with the leg-holes.

[0034] As will be apparent from FIG. 6, the waist-hole 6 opening upwardas viewed in FIG. 5 and the pair of leg-holes 7 opening left- andrightward also as viewed in FIG. 5 are defined as the front and rearwaist regions 20, 22 are bonded together along their transverselyopposite side edge portions 1 a, 1 b of the front and rear waist regions20, 22.

[0035] With the diaper 1 according to this embodiment, contraction ofthe respective elements 12 a˜ 12 d constituting the auxiliary elasticmember 12 causes an upper zone of the rear waist region 22 to beslightly drawn near toward the front waist region 20 and causes a lowerzone of the rear waist region 22 to be drawn nearer to the front waistregion 20 than the upper zone. The respective bonding zones 5 extendingalong the transversely opposite side edge portions 1 a, 1 b of the frontand rear waist regions 20, 22 from upper ends 5 a toward lower ends 5 bthereof so that these bonding zones 5 get nearer to the longitudinalcenter line X. With the diaper 1 put on the wearer's body, the upperends 5 a of the respective bonding zones 5 lie on transversely oppositeflanks of the wearer and the lower ends 5 b of the respective bondingzones 5 lie on the wearer's belly.

[0036] An alternative arrangement is also possible according to whichthe respective bonding zones 5 extend from the upper ends 5 a toward thelower ends 5 b getting nearer to the longitudinal center line X so thatthe lower ends 5 b may lie on the wearer's hip. Such arrangement will beconvenient when the diaper 1 is taken off from the wearer lying on hisor her face.

[0037] The topsheet 2 may be formed with a liquid-pervious sheet such asa nonwoven fabric or a porous plastic film, more preferably by aliquid-pervious and hydrophilic sheet. The backsheet 3 may be formedwith a hydrophobic nonwoven fabric, a liquid-impervious plastic film ora laminated sheet consisting of a hydrophobic nonwoven fabric and aplastic film, more preferably with a breathable and liquid-impervioussheet. It is also possible to form the backsheet 3 with a compositenonwoven fabric (SMS nonwoven fabric) comprising highly water-resistantand a flexible melt blown nonwoven fabric and two layers of spun bondnonwoven fabric sandwiching therebetween the opposite sheet surfaces ofthe melt blown nonwoven fabric.

[0038] The nonwoven fabric used for this invention may be of varioustypes such as spun lace-, needle punch-, melt blown-, thermal bond-,spun bond-, chemical bond- and airthrough- types. The component fiber ofthe nonwoven fabric may be selected from a group including polyolefine-,polyester- and polyamide-based fibers and core-sheath-, eccentriccore-sheath- and separated-type polyethylene/polypropylene or polyesterconjugated fibers.

[0039] The elastic members 9, 10, 11, 12 may comprise thread-,filament-, film- or ribbon-like elastomer of natural or syntheticrubber.

[0040] The panel 4 comprises a mixture of fluff pulp, high absorptionpolymer particles and thermoplastic synthetic resin fiber compressed toa desired thickness. The high absorption polymer may be selected from agroup including graft polymer of starch-based, modified cellulose-basedand synthetic polymers.

[0041] Bonding the top- and backsheets 2, 3 to each other or to thecuffs 8, bonding of the panel 4 and attaching of the elastic members 9,10, 11 maybe carried out by means of suitable adhesive such as a hotmelt adhesive or a pressure-sensitive adhesive, or using suitablewelding technique such as heat sealing or supersonic sealing technique.Use of the hot melt adhesive is particularly preferable as the adhesivemeans.

[0042] This invention is not limited to the disposable pull-on diaperbut applicable also to the other disposable pull-on undergarments suchas training pants or incontinent pants.

[0043] In the disposable pull-on undergarment according to thisinvention, the respective bonding zones extend from the upper endstoward the lower ends thereof, getting nearer to the longitudinal centerline so that the lower ends may lie on the wearer's belly or hip. Whenthe diaper is taken off from the wearer lying on his or her back or onhis or her face, the direction in which the force is exerted on thediaper to tear open this is substantially coincident with the directionin which each of the bonding zones extends and therefore substantiallyno force is exerted on any other zones than the bonding zones. As aresult, the diaper can be smoothly torn open along the respectivebonding zones.

What is claimed is:
 1. A disposable pull-on undergarment having frontand rear waist regions opposed to each other and a crotch regionextending between these two waist regions wherein said front and rearwaist regions are connected with each other in bonding zones extendingalong transversely opposite side edge portions thereof so as to define awaist-hole and a pair of leg-holes, wherein: said bonding linesrespectively have upper end portions lying adjacent said waist-hole andlower end portions lying adjacent said pair of leg-holes so that saidbonding lines get nearer to a longitudinal center line verticallyextending across a circumferential middle zones of said front and rearwaist regions as said bonding lines extend from said upper end portionstoward said lower end portion.
 2. The undergarment according to claim 1,wherein said bonding lines extend at an angle of 5˜30° with respect tosaid longitudinal center line.
 3. The undergarment according to claim 1,wherein said undergarment comprises a liquid-pervious topsheet, aliquid-impervious backsheet and a liquid-absorbent panel disposedbetween these two sheets.